Instrument for measuring angles



NOV. 22, 1927. 1,650,553

T. J. TRESIDDER INSTRUMENT FOR MEASURING ANGLES Filed Oct. 19, 1926tsaaa P NIr m a INSTRUMENT son lvrnasunrne Arteries.

Application filed October 19,1926, serial no. 142,672, and inoreatBritain January 15, i926. A

For measuring angles, such as those, of lathe centres, drills, or othertools, the choice of instrument has hitherto lain between (1) a fixedgauge, such as a notch in a plate, which is good for one angle only, or(2) a shifting gauge that can be set to any angle but has the greatdrawback that its two testing surfaces are not (loosely speaking) in thesame plane; that is, one of the said surfaces is not opposite the othersurface but is to the side thereof. The'object of the present inventionis to provide a'shifting gaugethat is free from this defect. I

The manner in which this invention may be carried out is bestdescribedby reference to the accompanying drawing which illustrates a typicalinstrument capable of gauging any external, or internahfangle up to 160degrees, and which can also be laid flat on a drawing board and used asa protractor,

Figure 1 is a front elevation of the complete instrument shewing it setto an angle of 90 degrees. c p

Figure 2 is a'vertical cross-sectional elevation through the centre ofthe pivot; Figure 3 is a vertical cross section of the body andpivotonly, through the centre of the pivot, shewing the initialarrangement or the latter in the body according to one method ofconstruction.

Figure 4 is a plan of the body as finished by machining its uppersurface, pivot and all, down to the exact level of centre of pivot, soas toleave of the latter only the portion that is below that surface orprojecting from the front of it.

Figure 5 is a rear elevation of the device" shewing an attachment forfacilitating the gauging of internal angles.

Figure 6 is an end elevation of this attachmentand of the device, y

The followingare the four essential parts of the instrument. a

(1) The body a, which in this case is a flat steel bar of rectangularsection but may be made of other material or shape suited to thepurpose. its face is preferably counter sunk, as shewn at a to the depthof the thickness of the segmental piece 0, so that the radial divisionsthereon maybe better read against an index line a on the said body a.(2) The wedge b, which may be of steel the same thickness as thethickness of the body a below the counter-sunk part a and may have itssides inclined to each other at A suitable thickness for it in Thiswedge rotates on its apex which is in contact with the upper surfaceofithe body a andcoincident with the axis of the pivot d, which alsolies in that surface. During this rotationthe apex of the wedge b has nomovement of translation, and the angle between the outer surface of thesaid wedgeand the upper surface of the body a can be' varied from zeroto 160 degrees and used for testing external angles within that range.

(3) The segmental piece 0 which lies in the'coun-ter-sunk part a of thebody 0;, 170- tates on the pivot (Z, has a circular slot to allow of itsbeing clamped to the said body in any position by a clamping screw g,and is fixed to the wedge 15 in any convenient way, say by two studs orsteady pins f 7" and a set-screw e. This screw e may convenient- 20degrees,

. ly be shaped to serve as a handle for varying does not permit theirseparation. The segmental piece '0 is preferably made from a sheet ofstitt material such as cast steel, ger man silver, phosphor-bronze, orthe like. a gauge of the sizeillustrated, whose body a is approximately3inches by 17 inches, is a full sixteenth of an inch. An index line a"against which angles are to be read, "is scribed on the body was shown.(4) The pivot 03. This might be turned out of the material of the bodyfawhenthe countersink a is being made, but a preferable method' is toturn the pivot block separately from a rod of good cast steel, reducingthe working part, or pivot proper, to approximately one eighth of aninch to three sixteenths of an inch in diameter for a' length justexceeding the thickness of the segmental piece 0 and making the rest ofthe block a little shorter than the thickness upper surface of-the bodya to be machined down to the level of the said upper surface as shewn inFigure 2. V

The remaining portions of the device are the milled-headed screw g withits washer h and flat coiled spring jwlhese need no explanation. V

For testing internal angles, such as a notch in template steel to form afixed gauge, an additional attachment is (see Figures 5 and 6) that maybe fixed to the body ain amoment with a'single milled-headed screw Z,can be provided. Its object is to allow one edge of .the. notch, broughtinto contact with the underside of the'projecting edge of lc,-to bethereby made lineable with the upper surface of thebody a by feel,

leaving only one edge to be dealt with by the less accurate sense ofsight. This attachment is not serviceable for angles under about 5degrees, as the wedge b then comes I 1 into'contact with it.

1 to which said .WhatIc1aimis;- @lQA shifting angle gauge comprising abod part, and a segmental piece carried by sai body part, in combinationwith a pin segmental piece is pivoted, said pin being secured to saidbody part at one of its surfaces, a oortion of said pin bein machineddown 0 its axis which lies in tie surface of said bodypart, and a awedge secured; to said segmental piece, the

apex ofsaid wedge and the axis of said pin beingv coincident.

2. A shiftingangle gauge comprising a body part, and a slotted segmentalpiece carried by said body part,-in combination with a pin to which saidsegmental piece is pivoted, said pin being secured to said body,

part at one-of its surfaces, a portion of said pin being machined downto its axis which lies in the surface of said body part, a wedge securedto said segmental piece, the apex of said wedge andrthe axis of said pinbeing coincident, and means for clamping the segsubstantially 13. Ashifting angle gauge comprising a body part, having a countersunkportion in one of its faces, and a segmental piece carbeing secured tosaid body part at ried in the countersunk portion of said body part, incombination with a pin to which. said segmental piece is pivoted, saidpin one of its surfaces, a portion of said pin being machined'down toits axis which lies in the surface of said body part, and a wedgesecured tosaid segmental piece, the apex of said wedge, and the axis ofsaid pin being coincident.

4. A shifting angle gauge comprising a body part'having a countersunkportion in one of its faces, a segmental piece carried in thecountersunk portion of said body part, radial markings adjacent the edgeof, said segmental piece, and an index marking upon said body'partagainst which said radial markings may be read, in'combination with apin to which said segmental piece is pivoted, said pin being secured tosaid body part at one of its surfaces, a portion of said pin beingmachined down to its axis which lies in the surface of said body part,

and a wedge secured to said segmental piece, the apex of said wedge andthe axis of said pin bein coincident.

5. A shifting angle gauge comprising a body part, and a circularlyslotted segmental piece carried by said body part, in combination with apin to which said segmental piece is pivoted secured to said body partat one of its surfaces, a portion of said pin being machined down to itsaxis which lies in the surface of said body part, in combination with apin to whichsaid segmental piece is pivoted, said pin being secured tosaid body part atone of its surfaces, a portion of said pin beingmachined down to itsaxis which TOLMIE JOHNZTRESIDDER.

